Influence of Processing Parameters on the Mechanical Properties of Peek Plates by Hot Compression Molding

Thermoplastic components are gaining more and more attention due to their advantages which include high specific strength, high toughness, and low manufacturing costs. Despite the fast development of such materials in engineering applications, the major challenge for the wider use of thermoplastic components is the diverse mechanical properties that are caused by uncertain factors during the molding process. In this paper, the effects of processing parameters on the mechanical properties of PEEK plates by hot compression molding are systematically investigated, including the temperature, pressure, and compression time. It was found that both temperature and time can sensitively change the mechanical properties; however, a pressure larger than 1.5 MPa showed a limited impact on the mechanical behaviors of PEEK plates. The optimal process parameters include a hot compression temperature of 400 °C, a compression time of 30 min, and a pressure of 2.5 MPa.     

Research on Dynamic Compressive Performance and Failure Mechanism Analysis of Concrete after High Temperature and Rapid Cooling

To investigate the dynamic compressive properties of concrete after high temperature and rapid cooling, an experimental study was carried out by considering five temperatures and four strain rates. The coupling effect of high temperature and strain rate on concrete damage morphology and mechanical parameters was comparatively analyzed. The main conclusions are as follows: the compressive damage morphology of concrete is affected by strain rate development trends of significant variability under different temperature conditions. As the strain rate increases, the compressive stress and elastic modulus of concrete are gradually increased. As the temperature increases, the increase in compressive stress is gradually reduced by the strain rate. For the temperatures of 20 °C and 800 °C, the increase in compressive stress by the strain rate is 38.69% and 7.78%, respectively. Meanwhile, SEM and CT scanning technology were applied to examine the mechanism of the effect of high temperature and strain rate on the mechanical properties of concrete from the microscopic perspective, and the corresponding constitutive model was proposed.     

A service evaluation to examine the use of compression strapping for the management of patients with retromalleolar leg ulcers in a specialist community setting

Leg ulcers are costly to the NHS, and they have a significant impact on patients'' physical, social, and psychological well‐being. Compression therapy is traditionally the “gold‐standard” treatment for the management of venous leg ulcers and can be beneficial for those individuals with mixed ulcer aetiology. Evidence suggests that the application of standard, strong, graduated compression bandaging does not apply therapeutic compression to the retromalleolar fossa. The addition of compression strapping has been found to increase sub‐bandage pressure, promote healing, reduce pain and increase quality of life in patients with retromalleolar leg ulcers. This service evaluation aimed at evaluating the use of compression strapping with patients with retromalleolar leg ulcers. The service evaluation included 24 patients with 41 ulcers treated with compression strapping by a specialist team. Patients treated with CS had multiple comorbidities and shared common characteristics including foot and ankle oedema, previous ulceration, reduced mobility, and failure to heal despite the application of “gold‐standard” compression therapy. Following application of compression strapping, 17 patients (n = 27/41 ulcers) healed, mean pain scores decreased, and mean quality of life scores increased. The compression strapping was tolerated well, and patients reported a positive experience. This service evaluation has contributed towards a growing evidence base that supports the use of CS for the management of patients with retromalleolar leg ulcers.     

MIPPO技术结合锁定加压钢板对A型闭合性胫骨远端骨折患者踝关节功能及活动范围的影响

目的 探讨微创经皮钢板接骨术(MIPPO)结合锁定加压钢板对A型闭合性胫骨远端骨折患者踝关节功能及活动范围的影响.方法 选取2017年2月至2020年2月收治的A型闭合性胫骨远端骨折患者48例作为研究对象,以数字法将其随机分为对照组和观察组,各24例.对照组采用普通接骨板治疗,观察组采用MIPPO技术结合锁定加压钢板治...     

基于影像学特征对骨质疏松性椎体压缩骨折病人经皮椎体成形术后同椎体再发骨折的预测研究

目的 探讨基于影像学特征对骨质疏松性椎体压缩骨折（OVCF）病人经皮椎体成形术（PVP）后的列线图模型预测术椎椎体再发骨折的价值。方法 回顾性纳入急性OVCF并行PVP后的病人93例。所有病人均行X线及MRI检查,根据椎体再发骨折诊断标准将病人分为再发骨折组（48例）和无再发骨折组（45例）。采用t检验和卡方检验比较2组间临床资料及影像特征的差异,对差异有统计学意义的指标进行多因素Logistic回归分析,获取再发骨折的独立危险因素,采用R软件建立列线图模型并绘制其校准曲线。采用受试者操作特征（ROC）曲线评估模型的预测效能,计算ROC曲线下面积（AUC）。应用校准曲线对列线图模型进行验证。结果 再发骨折组的椎体高度恢复率、延伸至终板的骨折线、椎体内裂隙（IVC）、骨水泥周围积液及骨水泥-终板未接触（NPEC）与无再发骨折组的差异均有统计学意义（均P<0.05）;多因素Logistic回归分析显示延伸至终板的骨折线[优势比（OR）=3.232]、存在IVC(OR=27.117)和NPEC(OR=1.993)及较高的椎体高度恢复率（OR=2.943）为同椎体再发骨折的独立危险因素（...     

Methods of Preparation and Performance Evaluation of ABS/Mineral Microsphere Composites Produced through FDM and Compression Molding

The use of amorphous microspheres as filler in composites is promising due to their light weight, low cost, incombustibility, and the ability to alter relevant properties of the final composite. Contrary to glass spheres, perlite microspheres are much cheaper and can be tailor-made to facilitate purpose-oriented alteration of the final composite. We report the use of perlite microspheres for the preparation of: (1) composites, through a compression molding (hot pressing) technique; and (2) composite filaments, in a single screw extruder, as well as their use for sample printing through Fused Deposition Modeling (FDM). Proper characterization of the produced composites allows for their evaluation in terms of physical, thermal, and mechanical properties and with regards to the manufacturing technique, the filler fraction, and size. Composite samples of acceptable quality in terms of filler survival and dispersion as well as mechanical properties were produced through compression molding using fine expanded perlite microspheres (<90 μm) up to an infill ratio of 40 vol.%. Fine fillers (<90 μm) performed well in FDM, allowing printing of composite dogbone samples with a higher Young’s modulus and elongation and similar ultimate tensile strength compared to benchmark, up to an infill ratio of 20 vol.%. Composite samples present a slightly lower burning rate compared to those produced solely by ABS. Perlite microspheres present good workability in both applications, possessing satisfactory performance as filler in the composites, and can thus be assumed a promising multifunctional filler for various thermoplastics considering their low price, environmental impact, and fire rating.     

Effects of compression bandaging on leg pulsatile blood flow

Leg external compression bandaging is the mainstay of venous ulcer treat-ment, yet little is known about the impact of therapeutic compression levels on arterial haemodynamics. In this study, the effect of foot-to-knee, four-layer compression bandaging on below-knee arterial pulsatile blood flow was assessed by nuclear magnetic resonance flowmetry. In 14 healthy supine subjects, bilateral flow measurements at five below-knee sites without compression, and after compressing one leg to an average malleolar sub-bandage pressure of 40·7±4·0 mmHg, revealed a potentially important new phenomenon. The forefoot-to-knee compression bandaging caused a highly significant (P<0·001) increase in the bandaged leg pulsatile blood flow owing to increases in both peak flow and pulse width. It is hypothesized that arteriolar vasodilatation, induced either myogenically by reduced transmural pressure or by vasodilatory substance release triggered by increased venous shear stress, produce the observed compression-related phenomenon. Whatever the mechanism(s), the finding of a compression-associated pulsatile flow increase suggests a previously undiscovered arterial linkage, which may play a role in the well-documented beneficial effects of compression bandaging in venous ulcer treatment. A possible impact of the arterial flow–pulse increase is speculated to effect venous ulcer outcome via a decrease in leucocyte effects in the distal microvasculature, as a consequence of the more vigorous haemodynamic state.     

彩色多普勒超声对假性动脉瘤的诊断和治疗

目的：本文旨在总结假性动脉瘤的彩色多普勒超声表现，并介绍彩色多普勒超声引导下的压迫治疗方法。方法：对１９９５～１９９８年我院经彩色多普勒超声诊断的１３例假性动脉瘤进行分析。在彩色多普勒超声引导下压迫治疗２例假性动脉瘤。结果：１３例假性动脉瘤病人中１１例经手术证实。另２例压迫治疗成功。结论：彩色多普勒超声对假性动脉瘤诊断准确率较高。彩色多普勒超声引导下压迫治疗假性动脉瘤是一种安全、有效的非介入性方法     

兔腰神经根慢性压迫模型的建立

目的 :制作腰神经根慢性轻度压迫模型。方法 :取纯种新西兰成年兔 16只 ,将 4只做神经定位解剖 ,12只随机分成 3组 :10天组、30天组和 180天组 ,每组 4只。将长 12mm ,内径 1.5mm ,外径 2 .5mm的硅胶管从椎间外孔缓慢塞入兔椎间管内 ,压迫腰 6和腰 7左侧神经根 ,右侧为自身对照侧 ,硅胶管的截面积约为椎间管经关节突关节矢状面面积的 2 0 % ,约为椎间外孔面积的 5 0 %。结果 :10天组与 30天组比较 ,潜伏时明显延长 ,神经传导速度减慢。180天组虽然与对照侧比较潜伏时和神经传导速度均有显著性差异 ,但与 30天组比较已有明显改善。对照侧的潜伏时、神经传导速度各时间点均无明显差异。除 10天组潜伏时、神经传导速度与对照侧比较无明显差异外 ,30天组和 180天组潜伏时、神经传导速度与对照侧比较均有明显差异 ,潜伏时延长 ,神经传导速度减慢。结论 :将硅胶管从兔的椎间外孔缓慢塞入椎间管内使腰神经根慢性轻度受压 ,更接近于腰椎间盘突出和椎间管狭窄对神经根的压迫。慢性压迫后的神经有自行恢复的能力。     

微创下中空加压螺钉内固定治疗锁骨骨折

目的探讨微创手术治疗锁骨中段骨折的方法及效果。方法对23例锁骨骨折采用微创下中空加压螺钉内固定治疗。结果所有患者均获随访,随访时间5～16个月(平均6.7个月)。X线示骨折愈合,愈合时间6～8周(平均6.6周),无畸形或延期愈合及并发症发生,外观良好,患者满意。结论微创下中空加压螺钉内固定治疗锁骨骨折是一种损伤小、操作简单、疗效优良的手术方法。